Two-dimensional (2D) semiconductors enable atomically thin channels and attractive electrostatics, but practical scaling increasingly hinges on gate-dielectric integration rather than channel performance. A key challenge is forming high-quality dielectrics on chemically inert, dangling-bond-free 2D surfaces while pushing equivalent oxide thickness to the sub-nanometer regime without excessive leakage, traps, or electrical breakdown. This review addresses the materials and process physics that govern dielectric formation in 2D devices, with an emphasis on atomic layer deposition nucleation, surface pretreatment and functionalization, and the use of seed and buffer layers for conformal high-κ oxides. The roles of layered insulators, such as hexagonal boron nitride, are discussed in terms of interface quality, electrostatic scaling limits, and transport limitations. The impact of dielectrics and processing on leakage mechanisms, defect generation, device-to-device variability, and reliability metrics, including time-dependent dielectric breakdown, bias-temperature instability, hysteresis, and threshold-voltage drift, is examined. Finally, we highlight van der Waals dry integration and dielectric transfer approaches that reduce process-induced damage and support wafer-scale uniformity, as well as opportunities for mixed-dimensional and 3D stacked architectures across logic, memory, and emerging functional systems.
NASA's Curiosity rover is exploring a 5 km tall sedimentary mound that is hypothesized to record the transition from a warm and wet (phyllosilicate-rich) to a cold and drier (sulfate-rich) Mars. Evidence of magnesium sulfate-bearing rock has shown that Curiosity has crossed through this phyllosilicate-sulfate transition. Recently, Curiosity arrived at the Amapari Marker Band, a darker, indurated unit that can be traced laterally for tens of kilometers in orbiter images. Here, Curiosity found evidence for a very broad lake, and bedforms interpreted as wave-ripple laminated sedimentary rock that likely was deposited in shallow water in the explored location, before becoming a deeper lake. These rocks are enriched in Fe, Mn, and Zn which has major implications for groundwater paleohydrology in Gale crater. Three formation hypotheses are considered: concretion formation during early diagenetic alteration of shallow lake sediments, laterization or leaching of the sediments, and addition of Fe, Mn, and Zn by a mildly acidic and reducing groundwater interacting with a redox and/or pH front in a stratified lake. The preferred interpretation of the metal enrichments within the Amapari Marker band sedimentary rocks is that they formed in a shallow water environment at a redox and/or pH front within the ripple unit, which drove precipitation and concentration of metals. If the enrichments are due to groundwater alteration, these processes could link subsurface and surface environments. Water and the presence of high amounts of redox sensitive elements and other metals are favorable indicators for habitability.
This study analyzes and contrasts different phenomenological methods used to model the nuclear equation of state (EOS) for neutron star matter based on covariant energy density functionals (CEDFs). Using two complementary methodologies, we seek to capture a comprehensive picture of the potential behaviors of ultradense nucleonic matter and identify the most plausible models based on current observational and experimental constraints. Observational data from radio pulsar timing, gravitational-wave detection of GW170817, and X-ray timing provide critical benchmarks for testing the models. We have derived the EOS posteriors for various CEDF models within the CompactObject package, utilizing recent observational data on neutron stars, state-of-the-art theoretical constraints from calculations in chiral effective field theory for pure neutron matter at low densities, and pQCD-derived constraints. Our analysis has demonstrated that while all considered CEDF models broadly reproduce current astrophysical and theoretical constraints, subtle yet important differences persist among them, with each framework exhibiting distinct characteristics at supranuclear density. This is particularly true for the proton fraction inside neutron stars, but is also supported by the models' behavior with respect to the pure neutron matter EOS and the density dependence of the speed of sound. Our study highlights the sensitivity of predictions for dense matter to the underlying EOS parameterizations and the priors considered.
Sample return missions play a significant role in planetary science by providing pristine extraterrestrial materials. JAXA's Hayabusa2 and NASA's OSIRIS-REx missions have returned samples from the C-type asteroids Ryugu and Bennu, respectively. The chemical and mineralogical compositions of these samples closely resemble those of CI chondrites, the traditional reference material for solar system abundances. Based on the findings of the Hayabusa2 mission, JAXA launched the Ryugu Reference Project (RRP) to maximize the scientific value of the returned samples and formed the RRP Measurement Definition Team (RRP-MDT) to elucidate the RRP's scientific goal and objectives. The RRP-MDT defined the goal of RRP to reassess the elemental abundances and isotopic compositions of the solar system through comprehensive analyses of the returned asteroid samples and CI chondrites. To this end, the team recommended preparing homogeneously powdered Ryugu reference materials (RRM) using approximately 750 and 400 mg of samples from Chambers A and C, respectively, to address observed compositional heterogeneities. The team proposed to measure the elemental abundances and isotopic compositions of the RRM by analytical techniques involving seven specific measurement groups. Through comprehensive analytical methodologies, interlaboratory calibration, and statistical evaluation, the RRP aims to refine our understanding of solar system formation and evolution.
